Electric furnace



-June 3, 1924. 1,496,440

v. M. WEAVER ELECTRIC FURNACE Original Filed March ll, 1918 4Sheets-Sheet l 27 l Z041' v legis `lune 3, 1924 V. M. WEAVER ELECTRICFURNACE 4 Sheets-Sheet 2 Im i7 Zlicf 77?. weaver fmfn n@ Original FiledMarch ll June 3, 1924. 1,496,440

v. M. WEAVER 4 ELECTRIC FUHNACE Original Filed March ll 1918 4Sheets-Sheet 5 June 3, 1924.

V. M. WEAVER ELECTRIC FURNACE Original Filed March ll, 1918 4Sheets-Sheet 4- www Patented June 3, 1924.

UNITED STATES PATENT OFFICE.

VICTO'R M. WEAVER, 0F THOROLD, ONTARIO, CANADA, ASSIGNOR TO WEAVER COH-i PANY, OF MILWAUKEE, WISCONSIN, A CORPORATION 0F WISCONSIN.

ELECTRIC FURNACE.

Application led March 11, 1918, Serial No. 221,630. Renewed January 21,1921.

To all whomy it may concern.'

Be it known that' I, VICTOR M. lVnAvnu, a citizen of the United States,residing; at Thorold, Ontario, Canada` have invented a .certain new anduseful Improvement in Electric Furnaces, of )which the following is afull, clear, concise, and exact description, reference being had t o theaccompanying drawings, forming a part of this specification. i

My invention relates to the art of forming desired chemical combinationsand has to do particularly with processes wherein it is necessary tomaintain a reducing atmosphere for the purposes of decompositionpreliminary to combination.

I am concerned particularly with the format ion of halides by thetreatment of a charge, such as an ore, which contains considerableoxygen, with a halogen gas and it is my purpose to provide for a mode ofoperation which at all times insures the formation of a monoxide gasinstead of a dioxide gas. It will be clear to those skilled in the artthat my invention is applicable, in itsbroader sense, to any rocedurewherein it is neces sary or desira le to secure a monoxide gas ratherthan a dioxide gas and it will be noted that the broader of the appendedclaims are accordin ly drawn. More specifically, I find special utilityand characteristic adaptability of this broad idea to the formation ofhalides, still more particularly chlorides, in which cases new functionsare performed. Accordingly it will be seen that I also make morespecific claims drawn to these more particular features which, in actualpractice, I have found to be extremely important.

As a specific instance of the desirablihty of insuring a monoxide gasinstead of a dioxide gas, for certain purposes, I make reference to myUnited States Letters Patent 1,238,604, issued August 28th 1917, whereina process of winning metals is described. There the teaching is tolsecure a monoxide gas and my present invention contemplates a new,effective and automatic Way of insuring it.

In a specific process described inl that patent aluminum chloride,silicon tetrachloride and carbon monoxide are formed by the action ofchlorine gas upon kaolin, in the presence of carbon, in a suitablefurnace.

Serial No. 439,049.

I shall use this specific process as an example in this descriptionforinstruction to those skilled in the art. If the amount of carbon weresufficiently limited, so that carbon dioxidel would be formed instead ofcarbon monoxide, a different result, involving the production ofcarbonyl chloride (phosgene) would result. This is all clearly set forthin my copending application, Serial No. 210,609, filed January 7, 1918.When, however, carbon monoxide is to be formed. instead of carbondioxide, as taught in my patent above referred to, it is obviouslynecessary to provide an excess rather than a deficiency of carbon, andmy present invention, as before stated, is directed to this end. Myinvention contemplates a carbon lined furnace, the carbon liningcomprising an inside part composed of closely united carbon in slabs orbricks or one large piece of closely `united carbon formed and baked inplace, and an outside or surrounding part composed of crushed or finelydivided carbon not cemented together. Such a lining has the propertiesof being infusible and of freely distributing the heat over the in sidepart of the lining and of preventing the loss of heat from the furnacethrough the outside part of the lining, and also provides at all timescarbon in contact with the gases after they have passed through thecharge. It is also has the property of being inert with respect to thehalides.

Owing to the carbon being inert with respect to the halides, I may usecarbon grate bars which are placed in such position vwith relation tothe Vheating zone that they will be maintained at a red heat.

A carbon hearth of crushed coke or the like is provided over the gratebars to support the charge and as a resistor for the electric current,thereby causing a. heating effect beneath the charge and in the path ofthe incoming gases.

To prevent excessive erosion of the inner carbon wall at the portionstouched by the charge, provision is made for furnishing additionalcarbonlin the form of c oal or coke in the sidechutes, which has' theeffect of maintaining a supply of carbon around the Walls, and therebyprotects them from the erosion above referred to.

In the specific process above referred to the charge, such as kaolin, isfed into the furnace with an adequate charge of carbon, whereuponchlorine gas is admitted and the action, under heat, proceeds. It' ispro posed that the same procedure shall follow vwith the use of mypresent furnace, but it will be seen that as my present furnace isconstructed the adequate charge of carbon is always insured. lf,perchance, the amount of loose carbon introduced with the kaolin shouldbe insufiicient to form carbon monoxide the carbon parts of the furnacethemselves will be attacked so as to insure the formation of themonoxide-an omnipresent safety device to avoid upsetting the intendedchemical procedure.-

Sofar as the process phase of my present invention is concerned, itconsists of insuring an excess of reducer by the constant presence of aredhot reducer element, in addition to the calculated charge andpreferably in different physical form. It is ,conceiw able that it mayalso differ chemically.

So far as the apparatus phase of my invention is concerned, it lies inthe construction of the furnace, providing, broadly, inherent carbonelements and, specifically, carbon lining, hearth and grate bars, or anyof them.

l shall now refer to the accompanying drawings, in which- Figurelillustrates diagrammatically the apparatus by means of which theprocess is carried out;

Figure 2 is a vertical longitudinal section partly diagrammatic of thefurnace empleyed for carrying out the invention;

Figure 3 is a plan view of the same on a reduced scale;

Figure'll is a verticallongitudinal section of the charging hopper.;

Figure 5 is a sectional detail view showing the covers for the coalchutes;

Figure 6 is an elevational view.y partly in sectionr showing theelectrodes, the adjusting mechanism for the same and the electrodeclamps;

Figure 7 is a side elevation on a larger scadle of a modified form ofelectrode clamp; an

Figure 8 is an end elevation of the same.

Figure 1, which is a diagrammatic outlay of a system for carrying outthe process of my invention, shows the chlorinizing furnece at 9. Thisfurnace, in which the reaction between the clay and carbon of the chargewith the chlorine occurs, is of the closed type.

The structure of the furnace and its electrodes is shown in Figures 2 to8 inclusive.

The furnace 9 comprises an outer shell or casing of sheet lmetal 10generally cylindrical in form having a smaller cyllndrical shell ofsheetl metal of considerably less diameter, as shown at 11, attached tothe Leeaeeo lower end where the chlorine is introduced at one of thenozzles 12. The top of the casv ing 10 is covered `by a reinforced sheetmetal top or cover 13 which has the braces of angle and channel iron14-15 for stitliening and supporting the same.

The interior of the furnace comprises a central bore 16, communicatingat its upper end with a charging hopper 17'and having a side outlet 18for discharging-v the gaseous products of the chemical combinationcarried on Within the furnace. The discharge opening 18 leads out by wayof a flanged nozzle 19 which communicates by Way of the discharge pipe20 with the double chamber 33, to be referred to later.

The entire inner facing of the furnace is composed of carbon. The wallor shaft of the furnace is constructed of carbon bricks or blocks laidin courses from bottom to near the top ot' the furnace.

The hearth 23 is composed of a bed of coke, or other porous mass ofcarbon supported on the carbon( grate bars 1.25. The charge 126 which inthis case comprises kaolin and crushed coke, both freed of moisture,rests upon the hearth 23.

Electrodes 22 project into the bore of the furnace :t short distanceabove the grate bars 125. The hearth 23 forms a resistor between saidelectrodes 22 and is maintained at a red heat by the passage of currentbetween the electrodes. The charge 126 is thus supported upon a hot massof carbon directly in the path of the incoming gases.

Above the hearth of the furnace 23 a plurality of coal feeding chutes 24are formed in the carbon walls 25. rlhese chutes comprise a lowerdiagonal portion converging into the main bore 16 and upper verticalportions 26 communicating at their upper ends with the filling openings27. formed in the cover plate 13 of the furnace. These cover platesmaybe left free to lift and act as relief valves in case of gasexplosions.

`The upper end of the main bore 16 is reduced 4by means otl the uppercourses of carbton blocks or bricks which extend inward to provide an oening suitable for the discharge opening o the charging hopper 17. Thespace between the carbon blocks or bricks and the metallic or sheetmetal shell 10 is filled with crushed carbon. rlhe centrai carbon liningis thus heat-insulated at the sides, top and bottom.

The top plate 17 is provided with a number of charging openings 27 inline with the vertical charging chutes 26. These charging openings 27are normally closed by a cover plate 72 seated upon annular rings 73. asillustrated in detail in Figure The closure between the cover 72 and therings 73 is made bv a lead gasket or other suitable material. The ring73 is suitably fastened as by means of rivets 76 to the cover plate 13.In the particular embodimentI that l have illustrated, six of thesecharging openings and siX of the charging chutes are employed. The sixelectrodes 22 pass into the hearth of the furnace, being supported uponthe sheetiron body 10 by the mechanism shown in Figure 6, which will bedescribed in detail later. These electrodes and the chargiiig chutesare'spacedfequally about the circumference of the turna-ce.

While the furnacey as shown provides vfor bringing in the electriccurrent by means ot horizontal graphite or plain carbon electrodes Icontemplate the use ot vertical or inclined electrodes in cases Wherethis is deemed more desirable.

The"charging hopper 17 comprises an upper receiving spout 77 Which isadapted to receive the material ot the charge, and which is closed by ahopper bottom 78 generally conical or :tunnel-shaped in contour, andhaving its bottom opening normally closed by meansv of the charging bell89. The upper bell 79 is apertured at the center to permit the passagetherethrough ot `a pipe 81 and is threaded to receive the end of thelarger ipe 82, which pipe 82 is the. stem of the be l 79. The stem 82 issecured to a flange member 83 which flange meniber is 'in turn connectedby suitable operating mechanism for raising and lowering the bell 79 toopen the hopper bottom 78, or t0 close the same. A cylindrical barrelportion 84 is secured to the flange 85 of the hopper bottom 78 andextends downward to engage the flange 86 of `the second hopper bottom87, which is of the general contour of the hopper bottom 78, previouslydescribed. A bell 89 closes the hopper bottom 87, this bell having as astem the pipe 81 which extends through and above the pipe 82 that formsthe stem of the bell 79. At its upper end the pipe 81 has a flange 90,to which suitable operating cables are connected for manipulating thebell 89:

The hopper bottom 87 provides a Water cooled valve seat for the bell '89as these parts face the interior ot the furnace. The

hopper bottom 87 rests upon a ring 91 secured to the top 17 of thefurnace. An enlargement is formed in the hopper bottom at this portionto provide the lnecessary seating surface for the ring 91 and also toprovide room for the pipe 92 to be imbedded in the Walls of the hopperbottom which terms the valve seat. The pipe 92 which extends outside ofthe valve`seat, as shown in Figure 3, is adapted to be connected to asource of cooling Water or other medium. This pipe is imbedded in thevalve seat by casting the metal about the same. The flange of the hopperbottom 87 is connected by a short cylindrical section 93' with the topplate 13 to form a tight joint between these parts.

A sounding or feeling rod 9a passes down through the pipe 81 and throughthe valve member 89, having a knob 95 at its lower end for protectingthe end of the rod and for closing otl' the hole in the bell member 89.To this endfthc vtop of the knob 95 is made conical and is adapted toseat around the conical edge otl the hole formed through the bell so asto close ott' any leakage around the rod 94. rlhis rod 94 is connected.to suitable lowering and raising mechanism so that the rod may be letdown to Yfeel the height ot' the charge inthe furnace.

The bottom section 11 ot the furnace is provided with a pair ot manholes96 and 97. These manholes are ot a suitable size to permit cleaning otthe Ifurnace after a run or for making repairs, or inspection or thelike.

The electrodes 22 are made ot graphite and are provided at theirouterend with metal caps 98 which in turn are connected by means of anadjusting rod 99 threaded at the outer end for 'feeding the electrode asby means of the hand-Wheel 100. '.l`he details of this construction areshown. in Figure 6. A cast metal flange or ring 101 is secured about theopening in the shell 10 through which the electrode 22 passes. flangedsleeve 162 made of insulation preferably vitritied pipe surrounds theelectrode 22 and serves to insulate it from the shell and lining of thefurnace. Water cooled guidingplate 108 is supported on but insulatedfrom the. ring 101 and serves vto guide the electrode 22 into theinsulating sleeve' 192.

layer of suitable insulation 'l0-t is interposed between the tlange ofthe guiding plate 193 and the supporting ring 191. rllhe bolts 105 whichsecure these parts vtogether are carefully insulated by means ot'washers and collars of insulation 108. The guiding plate is cored out asshou'n at 107 `to provide water cooling space Ylor ivater-cooling thecover plate and the electrode. A stuliing box 10S adapted to receivesuitable packing is provided in 'the guiding plate 108 and the stullingbox gland A199 co-operates with 'the stuffing box to maintain a. tightpacking about the electrode 22.

The adjusting mechanism which comprises the threaded hand Wheel and thethreaded stem 99 permits the electrodes 'to be ted into the furnace asthey are `con-` bolts 115. The interior of each half of the Y contactwith the same. Suitable'ridges 119V and 120, provided With screw sockets121 and 122 may be provided to facilitatesuch attachment of theelectrical conductors.

The operation of the furnace in connection with the other apparatus willnoW be described. The bore of the furnaceisfirst charged with loosecarbon, preferably in the form of coke to substantially the height ofthe hearth. The charge of material-in this case, clay, preferably in theform of kaolin of the approximate formula,A1,(Si04),'is first given apreliminary heating to drive off all of the moisture, being heated forthis purpose to a high temperature. VThe hot kaolin is then mixed withdried carbon such as crushed coke and conveyed in dump cars to thedumping spout 77 where it is received in the hopper 78, from thencedischarged by way of the bell in the hopper bottom into the interior ofthe hopper 17. The bell 79 is then closed and the bell 89 is opened todischarge the clay into the bore of the furnace. The coal chutes arecharged Awith crushed anthracite coal by opening the cover plate 7 2 andfilling the chutes substantialiy full of loose coal in such positionthat it will tend to settle down into the bore or hearth of the furnaceas space is made therefor. There is thus a composite mass of kaolin andcoal or carbonldeposited on the hearth if the furnace.

The kaolin and coal or coke are charged into the furnace in properproportions, so that the oxygen of the charge will be taken up by thecoal and coke thus introduced; but the carbon in the coal chutes is4pro- `vided to protect the side Walls in Contact with the charge incase all of the oxygen in these parts of the charge is lnot taken up bythe coal or coke provided as a part oi: 'the charge.

The nozzies 12 are connected by Way of a pipe 30 with a suitabie sourceof chlorine gas as indicated by the tank 31 the admission of chlorinebeing controiled by the valve 32. The chlorine gas is adapted to enterby Way of the lower section 11 and pass up through the loose bed of cokeinto the Zone of actiyity-at the hearth. when the furnace is operating.Assuming that the current is noW turned on and that the chlorine gas isdischarged into the active Zone the disintegration of the kaolin Withthe formation of aluminum chloride and silicon tetrachloride isaccomplished. This is due to the heat, the carbon, and the chlorine,which effect the reaction. The oxygen liberated from the kaolin uniteswith the excess of carbon to form carbon monoxide. So far as the degreeof heat is concerned, those skilled in the art Will, of course, beguided by the fact that such a degree of heat as effects reactionbetvveen the chlorine and the aluminum and silicon .is required, theeffective temperaturesrbeing Well known in the art. l might add, forWhat further assistance it may give, that Ihave/found thattemperaturesbetween 900 and 12000 centigrade are most eiiicient.

The reaction is as follows:

atisio, ,Meow/toi:

' iaioiaarssicriaieco The three gases thus formed naturally rise andpass out of the outlet opening 18, and, as illustrated in Figure areconducted to the condenser 33. This condenser is in the form of a doubleclosed chamber providing the compartment 34 and the compartment 35separated by a. partit-ion 36. The compartment 34 is provided with a.system of cooling pipes 37, 37 which extend downwardly through and fromthe top of the chamber andWhich are distributed throughout the entirespace of this particular compartment in order to get complet-etemperature control. Ther pipes 37, 37 are joined at the upper endsoutside of the chamber by means of the header pipe 38 and circulation issecured in any desirable manner. In this particular condenser elementthe system of pipes is connected to a. cold water supply and the resultis that as the three gases Which have-been referred to enter and passthrough the compartment 34 the aluminum chloride gas, which condenses ata higher temperature than the silicon tetrachloride gas, is condensedand deposits itself as a, White powder upon the pipes 37., 87. `hetemperatures at which these respective gases condense are, of course.well known in the art.. lt might he mentioned here that it is possiblethat in the action in the chlorinizing furnace some other chloride ofsilicon might incidentally be formed, a chloride such as hem/chloride(SigCl), but .ll find that conditions aressuch that it is only thesilicon tetrachloride vwhich plays any considerable part.

Where the clay contains oxide of titanium or other metals, the processof chloridization' Will make the chlorides of titanium and other metalsand carbon monoxide. i

Since the temperature which is.. produced by the circulation of merecold water in the voted to the condensation of the aluminum chloride andthe white powder to which it is reduced is removed from the pipes uponwhich it is deposited by means of the Scrapers 39, 39 which by 4meansgof pulley cords 40 passing over' suitable pulleys 41, 4l on the outsideof the condenser are drawn 'up-and down on the pipes to scrape them,

in an obvious manner. The powder is thus thrown down on the conveyor 42,the upper run of which passes in the direction `of the arrow 43, andthus the'condensed aluminum chloride is brought to ythe end of thecondenser element where the outlet 44 leading to a tank 45 is provided.This outlet may be controlled by a valve 46. It will be noted that thistank is connected by means of a pipe 47 with a compressed air tank 48,which is fed through the air compressor 49. It is important, as beforeindicated, that the system be a closed system and that various actionsbe carried on under pressure, and I speak of it particularly at thistime because of the fact that the aluminum chloride to which I have justreferred is extremely deliquescent and must be kept free from moisturein order to avoid decomposition and the formation of hydrochloric acid.When the system is' closed, however, such a result is not possible, andthe pressure has a p urpose to be referred tolater.

Leaving the aluminum chlorid, which has been deposited in the tank 45,for the present, I shall follow the course of the silicon tetrachloridas and the carbon monoxid through t e second element of the condenser.v

The condenser element 35 is provided with a system of cooling pipes 50like the pipes 37, t lese pipes having. the outside header 51 and beingprovided with the Scrapers 52, 52 hung from the pulley cords 53, 53,passing over the ulleys 5,4, 54. Instead of being supplied) with merecold water, however, the, cooling pipes 50 are supplied with a freezingmixture of ice water and salt, and the temperature in the condenserelement 35 is therefore considerably lower than the temperature in thecondenser element 34. The lower temperature is suiiicient to condensethe silicon tetrachlorid which comes down as a clear liquid, except forany impurities which may discolor- 1t. This liquid silicon 'tetrachloridpasses down the sloping bottom of the condenser element 35 andpasses'through the outlet 55, controlled by the valve 56 which leads to thetank 57. They condenser element 35 is provided with Scrapers as thecondenser element 34 is, because 1t is possible that the aluminumchlorid not en'- ,tirely condensed Vin its passage through the condenserelement 34A may condense upon the pipes 50 of they condenser element 35,and it is therefore desirable periodically to operate the scrapers52'inorder to remove this condensation. The Scrapers 39' :.-i the othercondenser element are operated during all the time that the system isbeing worked.

The condenser element 35 is provided withl a conveyor 58.

The carbon monoxide passes out of the condenser element 35 through apipe 59, past a valve 60 and to a closed gas pump 61, and is thencarried to a scrubber 62 by 'means of a pipe 63, thisscrubber being inthe form of a tank containing lime water and having an outlet pipe 63leading therefrom. This outlet pipe is provided with 'a valve 64 andleads to a telescoping gas tank 65 so that pressure may be kept upon thecarbon monoxide which finds its way to this tank and so that the carbonmonoxide maybe fed by way of a pipe 66 to a burner which may be used forheating. 4

It will now be seen that there will always be an excess of carbon toinsure the formation of carbontmonortide` rather than carbon dioxide, asabove pointed out, it being clear that should the loose carbonintroduced prove insufficient, the carbon elements of 'the' ,furnaceitself will respond. Beyond this the fact that carbon is used for thepurpose speciiied is important because of the characteristics of carbonalready pointed out.

As before indicated, my furnace and process may be employed, in broadersense, in connection with the production in any halide from oxygenbearing ores, compounds or mixtures, and, in fact, in a still broadersense, is applicable to any process wherein ay for said chamber, anentry for solid reducer forsaid chamber, a separate gas exit for saidleiamber, and means for heating said cham- 6. A furnace comprising aninteriorcarbon wall formingla chamber, .a charge entry for said chamber,anentry for solid reducer for said chamber, a gas exit for said chamberand electrical means for heating ,said chamber.

7. A furnace comprising an interior carbon wall forming' a chamber, acharge entry isov Mesem a' packing of heat insulating material betweensaid Wall and said housing. Y

9. A furnace lfor heating an oxyg'enbearing charge, comprising aninterior bore of carbon brickwork, a surrounding housing and a lling ofcharcoal between said brick- Work and said housing..

In Witness whereof, I hereuntoI subscribe my name this 28th day ofFebruary A. D. 20

1918. f VCTOR M. WEAVER.

